diff --git a/src/bank-account.scm b/src/bank-account.scm
index c5e8b39..7c2be1f 100644
--- a/src/bank-account.scm
+++ b/src/bank-account.scm
@@ -44,6 +44,8 @@
   bank-transaction-type
   bank-transaction-account
   bank-transaction-bank
+
+  bank-accounts-member?
   )
 
  (import scheme
@@ -85,4 +87,15 @@
 				 (bank-transaction-message tr)
 				 (bank-transaction-type tr))))
 
+ ;; Returns true if given acc/bc is in the list of accounts
+ (define (bank-accounts-member? bas acc bc)
+   (let loop ((bas bas))
+     (if (null? bas)
+	 #f
+	 (let ((ba (car bas)))
+	   (if (and (equal? acc (bank-account-number ba))
+		    (equal? bc (bank-account-bank ba)))
+	       #t
+	       (loop (cdr bas)))))))
+
  )